Gel Problems (all of a sudden)

dbruno

Hi - When I photograph using an on-camera Speedlight in a room lit with Tungsten ambient, I have been using a 1/2 CTS over the flash. I have been setting my camera (Canon 6D) to Tungsten, and it seemed to me like things were working out pretty OK.

The other night, I was photographing a symposium at a law school in a room with tungsten. One of the walls, directly opposite where the 6-person panel was seated, was a medium paneled. The other walls were off white. I was bouncing off any one of them depending on the shot. because I "thought" I had some issues in the past with brownish walls, when I bounced off the paneling, I removed the gel (sometimes). For the other shots, I put the gel on. I pretty much didn't get what I wanted at all

If/when you guys gel a flash, what do you set the in-camera WB to? Do you dial in a Kelvin setting?

When the gel was "out", I found myself reducing the blue slider (in LR), and when the gel was "in", I was reducing the yellow and orange sliders. This was all in an effort to make everything look consistent - the walls, the skin tones, the name placards, etc.

The thing I really go after is consistency from shot to shot. For some reason, this job was more work than I thought it would be.

So what to you "gellers" do?

Thanks - Dave

rs_eos

First, if you're shooting in RAW, the white-balance you set in your camera ultimately doesn't matter.  The RAW metadata will capture what that setting was, but it will not affect any of the image data.  If you shoot in RAW + JPEG or JPEG only, you're JPEGs will be messed up if you don't get the setting right.  Also, the image on the back of your camera will be a JPEG representation, so that will get affected too.

Having said that, it sounds like you're dealing with two issues; color casts and multiple color temps.  Will try to break that down.

First, 1/2 CTS will shift from 5500K (flash temp) to just 3800K.  Tungsten is closer to 3200K which can be achieved with 3/4 CTS or 3/4 CTO.   I don't have 3/4 CTS myself (not sure they make that), but you can always put two gels together (1/2 CTS plus 1/4 CTS).

So at least one issue is that the in-room lighting is now warmer than your flash.

The other is when bouncing flash off of non-neutral walls.  I'm no expert here since I rarely bounce flash (I have enough flash units and modifiers to directly light for my needs).  But, with brown walls, that will warm the light.

To help remedy the color casts, first figure out what the dominant light source will be and make sure to get that nailed down.  i.e. if your main light source will need to be bounced off of a warm surface, you may want to lessen the amount of CTO/CTS and maybe in some cases add a CTB to try to counteract it. 

Also pay attention too though to how much influence the available light will have on your image.  Depending upon this, you'd want to match that light source's temp as closely as possible.

Other ideas are to use custom white balance; very useful when there are too many different light sources of different temps.

Finally, to your question about what to set WB to when using gels...  There are two uses of gels; color correction and creative.  For color-correction, it ultimately depends on what specific gel you're using if there exists a preset that matches that.  e.g. 3/4 CTO being 3200K, so you can set camera to Tungsten.  I usually have my camera in manual Kelvin.  All my corrective gels have labels showing me the mired shift and target Kelvin value.

Note that during sunsets/sunrises the color temp of available light will change quite rapidly.  For those situations, I will move from 1/8 to 1/4 to 1/2 etc CTO and adjust the camera to match the target Kelvin values.

However, I sometimes use CTO or CTB to be creative.  i.e. shoots in the middle of the day that simulate sunrise/sunset.  This is now a creative use.  For that, no matter the gel, I aways leave my white balance at either 'Flash' or just set my custom Kelvin value to 5500K.

dbruno

Thanks, rs, I appreciate the time you took to respond.

I'm almost exclusively doing events, so I'm not setting up any off-camera lighting except for when there are formally-posed photos in front of a backdrop. So, I'm always bouncing my flash.

I think what's also happening is I'm trying to get the hang of suppressing uneven ambient light, bumping up my shutter to max speed, and making the on-camera flash do more of the work of lighting. Confusing as it relates to my original post, but I've been trying to do this more.

Dave